WASHINGTON – A growing number of politicians facing tough battles in November’s congressional elections will reap the benefits of unlimited political spending by super PACs dedicated solely to their campaigns.

Many of these amped-up PACs have been established by the candidates’ allies or their former aides.

Federal law prevents an individual from donating more than $2,600 to a congressional candidate for a primary or general election and prohibits candidates from accepting corporate or union money. Federal super PACs can accept unlimited amounts of corporate, union and individual donations but are required to operate independently of candidates.

Even so, many of the new PACs have close ties to their favored candidates.

For instance, GOP lawyer Charlie Spies this year established the Fund for Louisiana’s Future, to aid Sen. David Vitter, R-La. His wife, Lisa Spies, who runs a political fundraising firm, counts Vitter among her clients. In addition, the senator made an appearance at an “alligator hunt” fundraiser for the super PAC in September. (Charlie Spies also registered the super PAC at the state level to aid a possible Vitter gubernatorial bid in 2015 and is challenging state rules that cap donations at $100,000.)

Spies, who helped found a super PAC that backed Mitt Romney’s 2012 presidential bid, said the super PAC is a “vehicle for supporters for Sen. Vitter and his conservative leadership” to back his political future whether he decides to seek a third Senate term in 2016 or run for Louisiana governor.

Spies said the super PAC will help combat Democratic Party officials intent on doing “everything they can to stop” Vitter.

The Spies’ family involvement on both sides of the Vitter campaign is perfectly legal, he said. “We both are professionals with our own businesses and multiple clients, and they are kept separate,” he said.

Experts say the federal rules regarding coordination are so narrowly defined that as long as the candidates and super PACs don’t collaborate on specifics, such as where political commercials will air, most super PACs meet the legal definition of independence.

The politicians can attend super PAC fundraisers but cannot solicit donations of more than $5,000.

“The idea that somehow by writing the check to a super PAC, it isn’t going to affect the candidate is ridiculous,” said Bill Allison of the Sunlight Foundation, which tracks political money.

Spies said he and his firm are helping to set up at least 10 candidate-aligned political groups this year. He declined to name the politicians the new groups would benefit.

Super PACs aligned with individual presidential candidates pumped more than $238 million into the 2012 White House contest. The rapid expansion of candidate-specific super PACs in congressional races comes as both parties gear up for a fierce battle for control of the Senate. Many of the new PACs benefit Republicans, who need a net gain of just six seats to take control of the chamber.

Senate Republicans face additional pressure. Seven of 12 GOP incumbents up for re-election in November also face primary challenges from the right, and an array of Tea Party-aligned groups have pledged grass-roots and financial support to their opponents.

Among the candidate-specific super PACs launched in the past year:

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Texans for a Conservative Majority, which is helping Texas Sen. John Cornyn, the No. 2 Republican in the U.S. Senate. The super PAC’s president is Randy Cubriel, a former Cornyn aide. It has spent $70,000 so far slamming Cornyn’s primary challenger Rep. Steve Stockman, a conservative firebrand who trails Cornyn in polls and campaign money.

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In South Carolina, Katon Dawson, a former chairman of the South Carolina Republican Party, and political consultant Walter Whetsell started West Main Street Values PAC to support Sen. Lindsey Graham, another Republican up for re-election and facing a primary challenge.

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In Alaska’s red-hot Senate race, at least three super PACs have emerged. Put Alaska First reported spending more than $133,000 in December on behalf of Sen. Mark Begich, one of the Democrat’s most vulnerable 2014 incumbents. (In interviews, its treasurer has left open the possibility of working with other candidates, including Republicans.) Freedom’s Frontier super PAC is backing the Senate candidacy of Lt. Gov. Mead Treadwell, a Republican. Political consultant Art Hackney, meanwhile, has launched Alaska’s Energy/America’s Values super PAC, to aid another Republican, Dan Sullivan.

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Josh Robinson, a former chief of staff to Louisiana Rep. Bill Cassidy, is forming a super PAC to aid Cassidy’s challenge to Sen. Mary Landrieu, D-La. Landrieu, up for re-election in a state President Obama lost by more than 17 percentage points in 2012, is a top Republican target.

The Senate Majority PAC, a Democratic super PAC, already has spent more than $270,000 against Cassidy.

“We’ve already seen a lot of third-party groups on the other side trying to influence the Senate race for Sen. Landrieu,” Robinson said. “It’s incumbent upon us to put every resource we can on the field.”

Robinson said he already has the trust of Cassidy’s donors and supporters. There’s no improper coordination, however, he said.

While Cassidy remains a close friend, Robinson said: “We stopped working together years ago in an official or political capacity.”

Experts expect to see more super PACs emerging in more House races, too.

South Florida homebuilder Anthony Farhat said Thursday that he had raised $1 million for the Values are Vital super PAC he created in November to support a Republican challenge to Rep. Trey Radel, R-Fla., who pleaded guilty in November to misdemeanor cocaine possession.

His top choice: Paige Kreegel, a medical doctor who lost to Radel in the 2012 primary.

“I created the super PAC around the premise of not making the same mistake of sending the same person to Congress twice,” Farhat said.